Oxford Comma list

oxford-comma.js

/**
 * Take a list of items and combine them into a string, with an Oxford comma for the last item.
 * @param {string[]} list Items to list into a string.
 * @returns {string} Comma-separated list of items.
 */
function toOxfordCommaList(list) {
	let strList = '';
	if (list.length > 2) {
		list[list.length - 1] = `and ${list[list.length - 1]}`; // Inject "and" before the last item
		strList = list.join(', ');
	} else {
		strList = list.join(' and '); // A single value won't get a separator so we can use this for both one and two item values
	}
	return strList;
}

// Example:
const elements = ['Wind', 'Earth', 'Water', 'Fire'];
toOxfordCommaList(elements); // "Wind, Earth, Water, and Fire"